蜀南地区页岩气高精度三维地震采集实践

Practice of High-Precision 3D Seismic Acquisition for Southern Sichuan Shale Gas

摘要: 本文介绍并总结了在中国四川盆地蜀南地区，针对埋深较深(3000~4500米)的下志留统龙马溪组页岩气藏，实施高精度三维地震采集技术的实践与成效。研究指出，该地区地表、地下地质条件复杂，常规地震勘探技术难以满足“地质甜点”和“工程甜点”的精细预测需求。文章提出采用宽方位、高炮道密度、适中面元、小线距的“两宽一高”采集方案，并详细论述了最大炮检距、覆盖次数、面元尺寸、横纵比等关键观测系统参数的选择依据，包括利用波动方程正演进行照明度分析。通过在泸州、长宁等区块的实践应用，该技术获得了高品质的地震资料，显著改善了目的层弱反射的成像质量，提高了微幅构造和断裂的预测精度。最终，该技术实践有效支撑了水平井的钻井和压裂，取得了96.5%的箱体钻遇率和100%的地震符合率，验证了高精度三维地震勘探在深层页岩气勘探开发一体化中的重要价值和推广意义。

Abstract: This paper introduces and summarizes the practices and achievements of high-precision 3D seismic acquisition technologies deployed for deep-buried (3000~4500 m) Lower Silurian Longmaxi Formation shale gas reservoirs in the southern Sichuan Basin, China. The study reveals that conventional seismic exploration technologies fail to meet the requirements for fine delineation of geological sweet spots and engineering sweet spots due to complex near-surface and subsurface geological conditions in the study area. A “two-wide and one-high” acquisition geometry featuring wide azimuth, high shot-receiver trace density, moderate bin size and small line spacing is proposed herein. The selection criteria for key survey geometry parameters, including maximum offset, fold coverage, bin dimension and aspect ratio, are elaborated, incorporating illumination analysis based on wave equation forward modeling. Field applications in blocks such as Luzhou and Changning demonstrate that this technology yields high-quality seismic data, drastically improves the imaging of weak reflections from target formations, and enhances the prediction accuracy of microstructures and fractures. Ultimately, this technical practice provides robust support for horizontal well drilling and hydraulic fracturing operations, achieving a reservoir compartment penetration rate of 96.5% and a seismic matching rate of 100%. The results verify the critical value and broad popularization potential of high-precision 3D seismic exploration for integrated exploration and development of deep shale gas.